to cause (a person) to doubt his or her sanity through the use of psychological manipulation:

How do you know if your partner is gaslighting you?

Origin of gaslight

1800-1810

1800-10;gas + light1; def 4 in reference to the 1944 movie Gaslight, in which an abusive husband secretly and repeatedly dims and brightens the gaslights in the house while accusing his wife of imagining the flickering